1. Field of the Invention
A major contributor to air pollution are the combustion products of fossil fuels. Included among the combustion products is nitric oxide, which is involved in the formation of photochemical smog. The nitric oxide is oxidized in the atmosphere to nitrogen dioxide, which subsequently reacts with hydrocarbons in the presence of sunlight to form photochemical smog.
Combustion products from automotive internal combustion engines, fossil fuel power plants, process furnaces, incinerators, and the like all contribute to the production of nitric oxide. Control of nitric oxide production has been directed toward modifications in the combustion process or removal of the nitric oxide from the combustion products prior to discharge into the atmosphere.
There have been numerous efforts to effectively remove nitric oxide from combustion effluents. However, there are many constraints in an appropriate system. The actual concentration of nitrogen oxides is low, so that a chemical scavenger must be very efficient to be at all economical. Secondly, it is desirable that the removal be relatively simple with and relatively inexpensive. Finally, the products should be innocuous.
2. Description of the Prior Art
U.S. Pat. No. 3,900,554 discloses the use of ammonia for reducing nitric oxide.